Present day automatic high production foundry installations utilize high pressure squeeze molding machines to form cope and drag molds which are then cored, if necessary, and assembled to form completed foundry molds. The molds are then placed on a pouring and cooling conveyor for casting. After the casting has cooled, the mold is punched out to remove the sand and casting therefrom. The cope and drag flasks are then separated and recycled through the molding line.
In high production units for large size flasks, the molding lines may either be "in-line" or "cross-loop" systems. In a "cross-loop" system the cope and drag molds are generally molded separately in parallel conveyor systems each crossing a loop of a pouring and cooling conveyor. In an "in-line" system the molding line generally extends parallel to the pouring and cooling conveyor and the cope and drag flasks are conveyed through the molding line in sets of alternating cope and drag flasks. The molding machines are then next to each other on a single conveyor. Both "in-line" and "cross-loop" mold production units have been manufactured for many years by The Osborn Manufacturing Corporation of Cleveland, Ohio.
In conventional "in-line" molding systems the flasks are driven through the molding line by a number of clutch and brake operated powered conveyor rolls which require relatively sophisticated and expensive controls so that each flask will be properly positioned for the variety of operations which must be performed thereon.
Typically, the mold with the cool casting therein is placed on the entrance of the molding line and after the casting and sand has been punched from the mold, the cope and drag flask are cleaned and separated. The cope and drag are then set into the cope and drag molding machines which conventionally include a vertically elevating table which includes a pattern plate. The sand filled flask is elevated against a squeeze board to form the pattern impression on the lower face of the mold thus formed in the flask. The mold is then replaced on the molding line conveyor. Such molds now move to a coring station but between the mold and the coring station, the drag is inverted so that the pattern cavity in the mold face is facing upwardly. After coring, the molds are assembled with the cope on top and the drag on the bottom and then replaced on the pouring and cooling conveyor.
For each of the above described operations, the cope and drag flasks must be relatively precisely centered and must be slightly spaced from each other to avoid interference. Accordingly, when a power driven conveyor is employed, the conveyor itself and particularly the controls for the drives can become inordinately expensive in addition to being a very high maintenance item.
It would of course be desirable if the sets of cope and drag flasks could be simply pushed through the molding line in abutting relationship; however, some means must be found to center and separate the flasks for each of the above noted operations. Moreover, when the flasks are again indexed by pushing, the slack or spacing between the flasks will be taken up, and like the last car on a railroad train, a flask may be subjected to a substantial jolt or bump when the slack is taken out of the line. This can cause damage or disintegration to a mold previously formed and can of course damage a flask. Accordingly, molding lines which employ abutting flasks pushed along an idler conveyor have numerous drawbacks which limit both productivity and reliability.